import { Router, Request, Response } from 'express';
import bcrypt from 'bcryptjs';
import jwt from 'jsonwebtoken';
import { v4 as uuidv4 } from 'uuid';
import { z } from 'zod';
import passport from 'passport';
import { Strategy as GoogleStrategy } from 'passport-google-oauth20';
import { config } from '../config';
import { getDatabase } from '../database';
import { authenticate, AuthRequest } from '../middleware/auth';
import { authLimiter } from '../middleware/rateLimiter';
import { hashToken } from '../services/encryption';
import { sendVerificationEmail, sendPasswordResetEmail } from '../services/email';

const router = Router();

passport.use(new GoogleStrategy({
  clientID: config.google.clientId,
  clientSecret: config.google.clientSecret,
  callbackURL: config.google.callbackUrl || `${config.serverUrl}/api/auth/google/callback`,
  scope: ['profile', 'email'],
}, async (_accessToken, _refreshToken, profile, done) => {
  try {
    const db = getDatabase();
    const email = profile.emails?.[0]?.value || `${profile.id}@google-oauth.local`;
    const googleId = profile.id;
    const displayName = profile.displayName || email.split('@')[0];
    const avatarUrl = profile.photos?.[0]?.value || null;

    const existing = db.prepare('SELECT * FROM users WHERE google_id = ?').get(googleId) as any;
    let user = existing;

    if (!user) {
      const existingEmail = db.prepare('SELECT * FROM users WHERE email = ?').get(email) as any;
      if (existingEmail) {
        db.prepare('UPDATE users SET google_id = ?, avatar_url = COALESCE(?, avatar_url), updated_at = ? WHERE id = ?')
          .run(googleId, avatarUrl, Date.now(), existingEmail.id);
        user = db.prepare('SELECT * FROM users WHERE id = ?').get(existingEmail.id) as any;
      }
    }

    if (!user) {
      const id = uuidv4();
      const now = Date.now();
      let username = displayName.replace(/[^a-zA-Z0-9_]/g, '_').toLowerCase().slice(0, 30);
      const existingUsername = db.prepare('SELECT id FROM users WHERE username = ?').get(username);
      if (existingUsername) {
        username = `${username}_${googleId.slice(0, 6)}`;
      }

      db.prepare(`
        INSERT INTO users (id, email, username, password_hash, verified, google_id, avatar_url, created_at, updated_at)
        VALUES (?, ?, ?, ?, 1, ?, ?, ?, ?)
      `).run(id, email, username, 'google-auth', googleId, avatarUrl, now, now);

      const inserted = db.prepare('SELECT * FROM users WHERE id = ?').get(id) as any;
      user = inserted;
    }

    done(null, user);
  } catch (err) {
    done(err as Error);
  }
}));

const registerSchema = z.object({
  email: z.string().email(),
  username: z.string().min(3).max(30).regex(/^[a-zA-Z0-9_]+$/),
  password: z.string().min(8).max(128),
});

const loginSchema = z.object({
  email: z.string().email(),
  password: z.string().min(1),
});

const forgotSchema = z.object({
  email: z.string().email(),
});

const resetSchema = z.object({
  token: z.string().min(1),
  password: z.string().min(8).max(128),
});

const verifySchema = z.object({
  token: z.string().min(1),
});

router.post('/register', authLimiter, async (req: Request, res: Response) => {
  try {
    const { email, username, password } = registerSchema.parse(req.body);
    const db = getDatabase();

    const existing = db.prepare('SELECT id FROM users WHERE email = ? OR username = ?').get(email, username);
    if (existing) {
      res.status(409).json({ error: 'Email or username already taken' });
      return;
    }

    const id = uuidv4();
    const passwordHash = await bcrypt.hash(password, 10);
    const verificationToken = uuidv4();
    const now = Date.now();

    db.prepare(`
      INSERT INTO users (id, email, username, password_hash, verified, verification_token, created_at, updated_at)
      VALUES (?, ?, ?, ?, 0, ?, ?, ?)
    `).run(id, email, username, passwordHash, verificationToken, now, now);

    // Email is non-blocking - fire and forget
    sendVerificationEmail(email, verificationToken).catch(() => {});

    const token = jwt.sign({ userId: id, email }, config.jwtSecret, {
      expiresIn: config.jwtExpiresIn,
    } as any);

    const ua = req.headers['user-agent'] || '';
    const deviceInfo = ua.includes('Mobile') ? 'Mobile' : ua.includes('Chrome') ? 'Chrome' : ua.includes('Firefox') ? 'Firefox' : 'Browser';
    db.prepare('INSERT INTO sessions (id, user_id, token, device_info, ip, user_agent, last_active, expires_at, created_at) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)')
      .run(uuidv4(), id, token, deviceInfo, req.ip || '', ua, now, now + 7 * 24 * 60 * 60 * 1000, now);

    res.status(201).json({ token, user: { id, email, username } });
  } catch (error: any) {
    if (error instanceof z.ZodError) {
      res.status(400).json({ error: 'Invalid input', details: error.errors });
      return;
    }
    console.error('Register error:', error);
    res.status(500).json({ error: 'Internal server error' });
  }
});

router.post('/login', authLimiter, async (req: Request, res: Response) => {
  try {
    const { email, password } = loginSchema.parse(req.body);
    const db = getDatabase();

    const user = db.prepare('SELECT * FROM users WHERE email = ?').get(email) as any;
    if (!user) {
      res.status(401).json({ error: 'Invalid email or password' });
      return;
    }

    const valid = await bcrypt.compare(password, user.password_hash);
    if (!valid) {
      res.status(401).json({ error: 'Invalid email or password' });
      return;
    }

    const now = Date.now();
    const token = jwt.sign({ userId: user.id, email: user.email }, config.jwtSecret, {
      expiresIn: config.jwtExpiresIn,
    } as any);

    const ua = req.headers['user-agent'] || '';
    const deviceInfo = ua.includes('Mobile') ? 'Mobile' : ua.includes('Chrome') ? 'Chrome' : ua.includes('Firefox') ? 'Firefox' : 'Browser';
    db.prepare('INSERT INTO sessions (id, user_id, token, device_info, ip, user_agent, last_active, expires_at, created_at) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)')
      .run(uuidv4(), user.id, token, deviceInfo, req.ip || '', ua, now, now + 7 * 24 * 60 * 60 * 1000, now);

    res.json({ token, user: { id: user.id, email: user.email, username: user.username } });
  } catch (error: any) {
    if (error instanceof z.ZodError) {
      res.status(400).json({ error: 'Invalid input', details: error.errors });
      return;
    }
    console.error('Login error:', error);
    res.status(500).json({ error: 'Internal server error' });
  }
});

router.post('/logout', authenticate, (req: AuthRequest, res: Response) => {
  const db = getDatabase();
  const authHeader = req.headers.authorization!;
  const token = authHeader.substring(7);
  db.prepare('DELETE FROM sessions WHERE token = ?').run(token);
  res.json({ message: 'Logged out successfully' });
});

router.post('/forgot-password', authLimiter, async (req: Request, res: Response) => {
  try {
    const { email } = forgotSchema.parse(req.body);
    const db = getDatabase();

    const user = db.prepare('SELECT id FROM users WHERE email = ?').get(email) as any;
    if (!user) {
      res.json({ message: 'If the email exists, a reset link has been sent' });
      return;
    }

    const resetToken = uuidv4();
    const resetTokenHash = hashToken(resetToken);
    const expiresAt = Date.now() + 60 * 60 * 1000;

    db.prepare('UPDATE users SET reset_token = ?, reset_token_expires = ? WHERE id = ?')
      .run(resetTokenHash, expiresAt, user.id);

    try {
      await sendPasswordResetEmail(email, resetToken);
    } catch {
      // Email failure logged already
    }

    res.json({ message: 'If the email exists, a reset link has been sent' });
  } catch (error: any) {
    if (error instanceof z.ZodError) {
      res.status(400).json({ error: 'Invalid input' });
      return;
    }
    console.error('Forgot password error:', error);
    res.status(500).json({ error: 'Internal server error' });
  }
});

router.post('/reset-password', async (req: Request, res: Response) => {
  try {
    const { token, password } = resetSchema.parse(req.body);
    const db = getDatabase();
    const tokenHash = hashToken(token);

    const user = db.prepare(
      'SELECT id FROM users WHERE reset_token = ? AND reset_token_expires > ?'
    ).get(tokenHash, Date.now()) as any;

    if (!user) {
      res.status(400).json({ error: 'Invalid or expired reset token' });
      return;
    }

    const passwordHash = await bcrypt.hash(password, 10);
    const now = Date.now();

    db.prepare(
      'UPDATE users SET password_hash = ?, reset_token = NULL, reset_token_expires = NULL, updated_at = ? WHERE id = ?'
    ).run(passwordHash, now, user.id);

    db.prepare('DELETE FROM sessions WHERE user_id = ?').run(user.id);

    res.json({ message: 'Password reset successfully' });
  } catch (error: any) {
    if (error instanceof z.ZodError) {
      res.status(400).json({ error: 'Invalid input' });
      return;
    }
    console.error('Reset password error:', error);
    res.status(500).json({ error: 'Internal server error' });
  }
});

router.post('/verify-email', async (req: Request, res: Response) => {
  try {
    const { token } = verifySchema.parse(req.body);
    const db = getDatabase();

    const result = db.prepare(
      'UPDATE users SET verified = 1, verification_token = NULL WHERE verification_token = ?'
    ).run(token);

    if (result.changes === 0) {
      res.status(400).json({ error: 'Invalid verification token' });
      return;
    }

    res.json({ message: 'Email verified successfully' });
  } catch (error: any) {
    if (error instanceof z.ZodError) {
      res.status(400).json({ error: 'Invalid input' });
      return;
    }
    console.error('Verify email error:', error);
    res.status(500).json({ error: 'Internal server error' });
  }
});

router.get('/google', passport.authenticate('google', { session: false }));

const clientOrigin = process.env.SERVER_URL ? config.serverUrl : config.corsOrigin;

router.get('/google/callback',
  passport.authenticate('google', { session: false, failureRedirect: `${clientOrigin}/login?error=google-auth-failed` }),
  (req: Request, res: Response) => {
    const user = (req as any).user;
    const token = jwt.sign({ userId: user.id, email: user.email }, config.jwtSecret, {
      expiresIn: config.jwtExpiresIn,
    } as any);

    const db = getDatabase();
    const now = Date.now();
    const ua = req.headers['user-agent'] || '';
    const deviceInfo = ua.includes('Mobile') ? 'Mobile' : ua.includes('Chrome') ? 'Chrome' : ua.includes('Firefox') ? 'Firefox' : 'Browser';
    db.prepare('INSERT INTO sessions (id, user_id, token, device_info, ip, user_agent, last_active, expires_at, created_at) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)')
      .run(uuidv4(), user.id, token, deviceInfo, req.ip || '', ua, now, now + 7 * 24 * 60 * 60 * 1000, now);

    res.redirect(`${clientOrigin}/auth/callback?token=${token}`);
  }
);

router.get('/me', authenticate, (req: AuthRequest, res: Response) => {
  const db = getDatabase();
  const user = db.prepare('SELECT id, email, username, verified, created_at, password_hash, avatar_path FROM users WHERE id = ?')
    .get(req.userId) as any;

  if (!user) {
    res.status(404).json({ error: 'User not found' });
    return;
  }

  res.json({
    user: {
      id: user.id,
      email: user.email,
      username: user.username,
      verified: user.verified,
      created_at: user.created_at,
      hasPassword: user.password_hash !== 'google-auth',
      avatarPath: user.avatar_path || null,
    },
  });
});

export default router;